1. Field of the Invention
The present invention relates to a vacuum processing apparatus that includes a reactor in which plasma is generated and an electrically neutral excited active species (which will be referred hereinafter to as “radicals”) may then be produced from such plasma, and the processes such as, for example, the process of depositing a thin film on a substrate placed in the reactor, the process of finishing the surface of the thin film thus deposited, and the like may be performed on the substrate using those radicals.
2. Related Art
The vacuum processing apparatus in which the radicals are produced by generating plasma within the reactor, and the processes such as, for example, the process of depositing a thin film on the substrate placed in the reactor, the process of finishing the surface of the thin film thus deposited on the substrate in order to improve its film quality, and the like are performed using the radicals may be used in a variety of applications.
For example, a plasma enhanced CVD is used as a vacuum processing apparatus in which an appropriate silicon oxide film may be deposited at a low temperature as a gate insulating film in the production of a liquid crystal display using low temperature polysilicon type TFT.
As disclosed in our prior Japanese patent application now published under No. 2000-345349, a CVD apparatus is proposed as the vacuum processing apparatus in which radicals may be produced by generating plasma within the reactor, and the process such as the film deposition process may be performed on a substrate placed in the reactor (in this specification, the CVD apparatus disclosed in the above patent application is referred to as “RS-CVD apparatus” that stands for the Radical-Shower CVD apparatus, in order to distinguish this CVD apparatus from the usual plasma enhanced CVD apparatus.
In the RS-CVD apparatus described in Japanese Patent publication No. 2000-345349, it is proposed that radicals may be produced by generating plasma within the reactor, and the film deposition process may be performed on the substrate using the produced radicals and a film deposition gas.
Specifically, in the RS-CVD apparatus described in the patent publication No. 2000-345349, it is proposed that the apparatus may be used in the following manner.
Initially, the reactor may be internally divided into a plasma generating space and a film deposition process space (which is functionally equivalent to the substrate process space) that are separated from each other by means of a partitioning plate having a plurality of through-holes through which the radicals are allowed to pass, a gas is delivered into the plasma generating space for producing radicals which may then be delivered through the plurality of holes on the partition plate into the film deposition process space. Then, in the film deposition process space, the film deposition gas delivered directly into this space as well as the radicals delivered through the plurality of through-holes on the partitioning plate into the space react with each other, and the film deposition process is performed on the substrate (for example, a glass substrate having the size of 370 mm.times.470 mm) placed in the film deposition process space.
In the specification, the phrase “the film deposition gas delivered directly” into the substrate process space, that is, the film deposition process space should be understood to refer to the film deposition gas that may be delivered directly into the substrate process space, that is, the film deposition process space from outside the reactor, without contacting the plasma or radicals.
FIG. 1 represents the general construction of the conventional partitioning plate employed in the RS-CVD apparatus when it is used for depositing a thin film on the substrate as proposed in the patent publication No. 2000-345349.
The partitioning plate 14 contains a plurality of film deposition gas diffusion spaces 24a and 24b. Those film deposition gas diffusion spaces 24a and 24b communicate with each other, and are isolated from the plasma generating space above them. The film deposition gas diffusion spaces 24a and 24b also communicate with the film deposition process space below them through the film deposition gas diffusion holes 26 as shown in FIG. 1. The film deposition gas is delivered into those film deposition gas diffusion spaces 24a and 24b through a film deposition gas inlet connected to a film deposition gas delivery pipe, is diffused through the film deposition gas diffusion spaces 24a and 24b, and is supplied uniformly into the total area of the film deposition process space through the film deposition gas diffusion holes 26.
The partitioning plate 14 further has a plurality of through-holes 25 that pass through the locations where the film deposition gas diffusing spaces 24a and 24b are not provided from one side toward the other side (in the vertical direction in FIG. 1).
As the reactor is internally divided into the plasma generating space and the film deposition process space that are separated from each other by means of the partitioning plate 14 constructed as described above, the radicals that have been generated in the plasma generating space may only be delivered into the film deposition process space through the through-holes 25, while the film deposition gas that has been delivered into the film deposition gas diffusion space 24a and 24b from outside the reactor may be delivered directly into the film deposition process space through the film deposition gas diffusion holes 26, without contacting the plasma or radicals until.
The vacuum processing apparatus, such as the RS-CVD apparatus as proposed in the patent application 2000-345349 for depositing a thin film on a substrate, wherein the reactor is internally divided into the plasma generating space and the substrate process space that are separated from each other by means of the partitioning plate having the plurality of holes through which the radicals are allowed to pass, the radicals may be produced using the plasma generated by delivering the gas into the plasma generating space, those radicals may be delivered into the substrate process space through the plurality of holes on the partitioning plate, and the process such as the film deposition process may be performed on the substrate placed in the substrate process space, remains yet to be improved as described below.
For the conventional partitioning plate employed in such vacuum processing apparatus as shown in FIG. 1, the surface of the partitioning plate 14 located on the plasma generating space may be hit by the plasma discharge, causing the surface to be deteriorated. If such surface deterioration should occur, the partitioning plate 14, which contains the plurality of film deposition gas diffusion spaces 24, would have to be replaced as a whole.
When the plasma discharge conditions are to be modified to meet the particular processing requirements for a substrate placed in the substrate process space and if such plasma discharge conditions are then to be modified by changing the sizes of the individual radicals passage holes 25, the partitioning plate 14 would also have to be replaced as a whole.
Having to replace the partitioning plate as a whole only because the surface of the partitioning plate on the plasma generating space side has been deteriorated as described above would lead to the increased running costs for the vacuum process apparatus.
It may be appreciated from FIG. 1 that the partitioning plate 14 that is employed in the RS-CVD apparatus described above takes the form such that it contains the plurality of film deposition gas diffusion spaces 24 that are separated from the plasma generating space and leading to the film deposition process space in order to permit the film deposition gas to be delivered directly into the film deposition process space from outside the reactor. More specifically, the partitioning plate 14 includes a plurality of plates stacked one over another, and there may be a gap between any two adjacent plates through which the radicals may enter the film deposition gas diffuse space 24, causing the radicals to react with the film deposition gas by contacting the same inside the partitioning plate 14.